Yes, there are some out there. Some fanfictions explore this alternative relationship dynamic in interesting ways. They might rewrite the story's events and character interactions to make it seem more plausible for Harry to be with Hermione instead of Ron.
The plot could start with Harry realizing he has deeper feelings for Hermione than just friendship. He might start spending more time with her, which causes tension between him and Ron. Eventually, he could confess his feelings to Hermione, and she might be conflicted because of her relationship with Ron.
If Draco steals Hermione from Ron in fanfiction, it might show a different side of Hermione. She might be attracted to Draco's intelligence in a different way than Ron's loyalty. This could lead to new magical adventures where Hermione uses her knowledge in a more Slytherin - like way, influenced by Draco. It could also make for some interesting interactions between the Gryffindors and Slytherins, as now there's a connection between them through Hermione. The story could explore how love can cross house boundaries in a more extreme way than what we see in the original books.
One possible reason could be that she is in a desperate situation. Maybe she needs something for a very important spell or potion to save someone's life and she thinks Harry won't notice or will forgive her. For example, if there is a rare ingredient that only Harry has access to and time is running out.
Maybe she's desperate for some knowledge that she thinks Harry has in those books. For example, if the books are related to some dark magic or ancient spells that she wants to study for the greater good, she might be tempted to take them without asking.
Ron would be furious. His best friend being 'stolen' by his former rival would make him feel a mix of anger, betrayal, and jealousy. Harry would probably be in a difficult position. He's friends with both Ron and Hermione, so he might try to mediate at first, but if Draco is being difficult, he'd side with Ron. Ginny would be protective of her brother and would likely be very critical of Hermione for choosing Draco. The Slytherins, on the other hand, might be initially shocked but then accept it as Draco asserting his power and getting something he wants.
Yes, there are some fanfictions out there on this topic that are quite well - written without crossing any inappropriate lines. Some authors use this as a creative exploration of different character dynamics, often delving into how the relationships could change under different circumstances.
If Hermione realizes her mistake and tries to make amends, it could lead to a deeper understanding between them. They might have to work through their feelings and have some difficult conversations. For instance, Hermione might have to explain her reasons fully, and Harry would have to decide if he can forgive her.
I'm sure there are. Fanfiction is a vast world where all kinds of scenarios are explored. A 'Ron cheats on Hermione' fanfic might be written to show the vulnerability of their relationship or to introduce new plotlines. But it's not something that would be acceptable in the context of the original story. It can be an interesting read for those who like to see different interpretations of the characters, but it also might be a bit controversial among die - hard fans of the original relationship.
At first, Harry would be angry and confused. But as the story progresses, if Hermione has a valid reason for stealing the grimoire, they could start to repair their relationship. However, there would always be a shadow of doubt and a sense of unease between them. For example, Harry might be hesitant to share important things with Hermione in the future.
The fanfic should also have an emotional depth. It should make the readers feel the love, the tension, or the friendship between them. For example, when they have an argument, the readers should be able to feel the pain and the longing to make up. And when they are happy together, it should be palpable, like their first kiss or a special moment they share that really showcases their relationship.